1. Field of the Invention
The invention is directed to an electric drive unit and particularly to such drive units useful in motor vehicles.
2. Description of the Prior Art
From German patent disclosure DE 32 35 622 A1 and U.S. Pat. No. 4,572,979, a design of an electric drive unit is known. Among other elements, it comprises an electric motor with a stator and a magnet in a pole housing, a rotor with an armature, and a gear in a gear housing. The pole housing and gear housing are joined together, making for a high number of parts to be assembled and high production costs.
The gear housing is made from plastic.
In the prior art, the motor housing either has a pole piece or is a pole housing that takes the form of a cup of a magnetically conductive material and thus acts as a pole piece. In both cases, two magnetic half shells are mounted on the inside in the housing. They are partly fixed by retention springs in the pole housing and/or, because of the incident vibration and also to reduce noise, they are adhesively bonded between the magnet and the pole housing.
The pole pot bottom contains a cylindrical or homelike bearing, which acts as a radial bearing for supporting the rotor.
After their manufacture, these parts, comprising an electric motor, magnet and bearing, exist in the form of separate components or a component group that have to be connected to the gear housing by screws or wedging.
Often, to reduce the longitudinal armature play, a spacer is also mounted between a face end of the rotor and a bearing in the pole housing, in order to compensate for tolerances of the rotor and pole housing.
From German patent disclosure DE 43 20 005 A1 and U.S. Pat. No. 5,895,207, it is already known to make the pole housing of an electric drive unit of plastic and for the magnets to be retained in the plastic. However, the gear housing and the pole housing are screwed together.
From German patent disclosure DE 197 24 920 A1, it is already known to accommodate a motor and a substantial portion of the gear in one housing. A separate gear housing is always still necessary, however. Furthermore, this reference provides no information about how the motor is accommodated in the housing or what material comprises the housing.